Impulse storage and regenerating polar duplex impulsing telephone system



5 Sheets-Sheet l J. WICKS INVENTOR. JOHN WICKS ATTORNEY IMPULSE STORAGEAND REGENERATING POLAR DUPLEX IMPULSING TELEPHONE SYSTEM Feb. 17, 1953Filed April 15, 1951 N OI \.mo FM. $9 99 30. TNmQ wmQ W o m o 10 m 2. awmm 39 oz, 0% ow oom J. WICKS IMPULSE STORAGE AND REGENERATING POLAR Feb.17, 1953 DUPLEX IMPULSING TELEPHONE SYSTEM 5 Sheets-Sheet 2 Filed April13, 1951 Jmm 02- INVENTOR. JQHN WICKS ATTORNEY r-n FIG. 7

Feb. 17, 1953 J WICKS 2,629,018

IMPULSE STORAGE AND REGENERATING POLAR DUPLEX IMPULSING TELEPHONE SYSTEMFiled April 13, 1951 5 Sheets-Sheet 5 ALM.

" 0o Q E INVENTOR. Q JOHN WlCKS ATTORNEY Patented Feb. 17, 1953 IMPULSESTORAGE AND REGENERATING POLAR DUPLEX IMPULSING TELEPHONE SYSTEM JohnWicks, Biloxi, Miss, assignor to Automatic Electric Laboratories, 1110.,Chicago, 111., a corporation of Delaware Application April 13, 1951,Serial No. 220,874

15 Claims. 1

The present invention relates to automatic or semi-automatic telephonesystems in general, and has for its principal object the provision ofimproved arrangements for intercepting, storing and regeneratingreceived impulses and for transmitting regenerated impulses, dependingupon the nature of the switching operations to be performed.

The following patents are cited as showing the state of the artpertaining to the control of automatic switches in a trunking network,through the use of a simple mechanical impulse repeater or regeneratorfor storing, regenerating and retransmitting the setting impulses over aloop circuit or talking channel: 2,154,776,

W. Saville et al., April 18, 1939; 2,211,443, R. F. Stehlik, August 13,1940; and 2,232,189, R. Taylor et a1., February 18, 1941.

An oustanding feature of improvement in the present invention over thedisclosures in these patents resides in the new and novel impulsesregenerating arrangement wherein the impulses are received andretransmitted over a separate control conductor independent of the holdconductor and the talking channel, thereby clearing the talking channel.

Another feature of the present invention resides in the provision of anew and novel relay network incorporating a simple mechanicalregenerating device for intercepting, storing and regenerating receivedimpulses and for transmitting regenerated impulses of correct speed andpulse ratio, which network can be interposed between various units of anexisting polar duplex impulsing telephone system without requiringchanges therein.

A further feature of the present invention concerns a new and novelimpulse regenerating network for polar duplex impulsing telephonesystems which is automatically disconnected from the connection uponreceipt of the answer signal and can, therefore, be either common to agroup of trunk circuits or be individually associated with one trunkcircuit.

Other features of the present invention pertain to the particulararrangements of the circuit elements of the system whereby theabove-outlined and additional operating features thereof are attained.

The various objects and features of the present invention will beunderstood best by reference to the following specification inconnection with the accompanying drawings which show preferredembodiments of the present invention by way of example.

Referring now to the drawings, Figure 1 is a block-type diagram of aportion of the polar duplex impulsing telephone system disclosed in theJ. Wicks Patent No. 2,500,392, granted March 14, 1950, showing anapplication of the present invention to the mentioned polar dupleximpulsing telephone system.

Figure 2 is a block-type diagram illustrating the method of combiningFigures 7 to 10, inclusive, to form unified circuit diagrams.

Figure 3 illustrates the method of combining Figures 7 and 8 to form acircuit combination wherein the present invention is made common to agroup of trunks of the polar duplex impulsing telephone system, andwherein the transmitting of the regenerated impulses is not delayed.

Figure 4 illustrates the method of combining Figures 7, 8 and 10 to forma circuit combination wherein the present invention is made common to agroup of trunks of the polar duplex impulsing telephone system, andwherein the transmitting of the regenerated impulses is delayed.

Figure 5 illustrates the method of combining Figures 7 and 9 to form acircuit combination wherein the present invention is made individual toone of the trunks of the polar duplex impulsing telephone system, andwherein the transmitting of the regenerated impulses is not delayed.

Figure 6 illustrates the method of combining Figures 7, 9 and 10 to forma circuit combination wherein the present invention is made individualto one of the trunks of the polar duplex telephone system, and whereinthe transmitting of the regenerated impulses is delayed.

Figures '7, 8, 9 and 10 show the circuit details of the presentinvention.

Figure 7 shows an impulse regenerating unit comprising a mechanicalimpulse regenerating device, illustrated at the right-hand end of thedrawing, and a group of relays for preparing and controlling themechanical impulse regenerating device.

Figure 8 shows a rotary selector unit which functions to connect one ofthe toll trunks of the polar duplex impulsing telephone system with afree one of a group of impulse regenerating units, the group of impulseregenerating units being common to all of the toll trunks of the polarduplex impulsing telephone system.

Figure 9 shows a relay connecting unit for connecting and releasing theindividual impulse regenerating unit of Figure 7 which is associatedwith a particular one of the toll trunks of the polar duplex impulsingtelephone system.

Figure 10 shows an additional group of relays which is associated withthe impulse regenerating unit of Figure '7 when the transmitting of theregenerated impulses is to be delayed.

Referring more particularly to Figure 1, there is illustrated, in blockform, only the elements of the polar duplex impulsing telephone systemdisclosed in the mentioned J. Wicks Patent No. 2,500,392 which arerequired for the completion of a call from the manual switchboard 2H]located in one of the telephone exchanges to the telephone substationT60| located in the distant telephone exchange, the two exchanges beingconnected together by means of a toll trunk represented by the referencecharacter 380. All of these elements of the polar duplex impulsingtelephone system shown in Figure 1 of the patent drawings are identifiedby the same reference characters used in Figure 1 of Patent No.2,500,392 for the equivalent elements and, therefore, reference can behad to the specification of Patent No. 2,500,392 for a completedescription of the particular elements shown in Figure 1 of the presentdrawings and for an explanation of the related method of operation.

The impulse regenerating network of the present invention is applied tothe polar duplex impulsing telephone system of Patent No. 2,500,392, forexample, by inserting either Figure 8 or Figure 9 of the presentdrawings between repeater 40D and incoming selector 500 of the polarduplex impulsing telephone system, in the manner shown in Figure l ofthe present drawings. It should be understood, however, that eitherFigure 8 or Figure 9 of the present drawings can be inserted betweenother units of the polar duplex impulsing telephone system equally aswell.

Figure 8 in combination with Figure '7 of the present drawings isutilized for the condition wherein the impulse regenerating network ofthe present invention is made common to a group of trunks of the polarduplex impulsing telephone system, and wherein the transmitting of theregenerated impulses is not delayed. Figure 8 in combination withFigures '7 and 10 of the present drawings is utilized for the conditionwherein the impulse regenerating network of the present invention ismade common to a group of trunks of the polar duplex impulsing telephonesystem, and wherein the transmitting of the regenerated impulses isdelayed to provide additional trunk hunting time.

Figure 9 in combination with Figure '7 of the present drawing isutilized for the condition wherein the impulse regenerating network ofthe present invention is made individual to one of the trunks of thepolar duplex impulsing telephone system, and wherein the transmitting ofthe regenerated impulses is not delayed. Figure 9 in combination withFigures '7 and 10 of the present drawings is utilized for the conditionwherein the impulse regenerating network of the present invention ismade individual to one of the trunks of the polar duplex impulsingtelephone system, and wherein the transmitting of the regeneratedimpulses is delayed to provide additional trunk hunting time.

A suitable mechanical impulse repeater, or regenerating device, for usein the present invention, in disclosed in the J. W. McClew et a1. PatentNo. 2,188,461 granted January 30, 1940, to which patent reference can behad for a detailed description of the device. It should be understood,however, that the present invention is not limited to a regeneratingdevice of this precise construc- 4 tion and that the use of any form ofimpulse registering device which functions to store a plurality ofseries of impulses and is effective to repeat the impulses iscontemplated.

The rotary selector shown in Figure 8 may be of any conventional designwherein the selector has no normal, or home, position and wherein thecircuit thereof is arranged in accordance with the present invention sothat the selector selfdrives its wipers over the related bank contacts.

Regenerating network common to a group of trun7csno delay in impulsere-tmnsmission As previously indicated, Figure 3 of the present drawingsshows that Figures '7 and 8 are combined together to form an impulseregenerating network Which is made common to a group of toll trunks of apolar duplex impulsing telephone system when the transmission of theregenerated impulses is not delayed.

Assuming now that such an impulse regenerating network is required, thenone selector unit 800, as shown in Figure 8, is provided for each of thetoll trunks of the polar duplex impulsing telephone system. The outgoingconductors C421, C422, C423 and C424 of each toll trunk of the polarduplex impulsing telephone system are connected to the respectiveincoming selector 508 of the toll trunk and the respective selector unit800 of the regenerating network, and the incoming selector 500 of eachtoll trunk and the respective selector unit 800 of the regeneratingnetwork are connected together, as shown at the left-hand end of Figure8.

Assuming further that two impulse regenerating units 700, as shown inFigure '7 of the present drawings, are required for the traffic over thetoll trunks of the polar duplex impulsing telephone system, thenterminals 74|744 of both impulse regenerating units 780 are made commonto the wipers 8 li844 of each selector unit 35!], as shown in Figure 8of the present drawings. In this manner, the two impulse regeneratingunits 7'68 are made available to each toll trunk of the polar dupleximpulsing telephone system. It should be understood, however, that anyrequired number of impulse regenerating units 700 can be provided tocare for the trafiic over the toll trunks of the polar duplex impulsingtelephone system, by making the terminals IN-744 of each impulseregenerating unit 700 available to the wipers B ll-844 of each selectorunit 800.

Picking up the description in the specification of Patent No. 2,500,392of the call from switchboard 2I0 to the called substation TSGI at thepoint when signal relay R475 of repeater 400 is first operated, adescription of the operation of the call as it passes through theimpulse regenerating network comprising Figures 8 and 7 of the presentdrawings will now be given.

The operation of signal relay R475 completes a circuit from battery,winding of control relay R445, contact 476, lower winding of supervisoryrelay R450, contact 544, conductor C424 in Figure 8, contacts 133i, 822,winding of relay 810 to ground. Relay Bill and control relay R445accordingly operate, but supervisory relay R450 does not operate becauseboth windings of supervisory relay R450 are now energized and relay R450is of the differential type. Control relay R445 operates busy relay R438over an obvious circuit. At contact 434, busy relay R430 connects groundpotential to conductor C423, and

this ground potential is extended through VON spring 'set S519 ofincoming selector 585 to the upper winding of transfer relay R568.Transfer relay R5656 accordingly operates, and by this action incomingselector see is seized from repeater Mill.

If at the moment that relay 82d of the selector unit 8% under discussionoperates over the related 032d conductor, the impulse regenerating unitlull connected to the wipers B ll-41M of the selector unit 863 underdiscussion is in prior use from another one of the toll trunks of thepolar duplex impulsing telephone system, then there will be groundpotential on the t lt wiper of the selector unit see under discussion.Ihis ground potential on wiper 3 54 of the selector unit 8139 underdiscussion will energize the related motor magnet 3 5 through contacts8H and interrupter contact and energized magnet 835 will self-drive itswi ers Evil-3M to the terminals of the next impulse regenerating unitled in well-known manner,

If, on the other hand, at the moment that relay 8ill of the selectorunit 8% under discussion-operates over the related C iZ l conductor, theimpulse regeneratin unit connected to the wipers 3 5 s art of theselector unit see under discussion is in the free condition, then therewill be no ground potential on the t l wiper of the selector unit underdis. .ission. A5 a consequence, the related motor magnet 835 is notenergized and, therefore cannot drive wipers 8ll-lid l or" the selectorunit under discussion from the terminals i 'lli l oi the impulseregenerating unit tilt shown in Figure 7.

Returning now to the description of the call in progress, and assumingthat the impulse regenerating unit (til shown in Figure '7 is not inprior use, then wipers ii il-d lt of selector unit 8% shown in Figure 8remain connected to terminals Mil-44st of impulse regenerating unit "we.Relay 8H3 of selector unit 0.. has operated over the circuit pathpreviously described and, since there is no ground potential on terminali lt of impulse regenerating unit ltd to short-circuit relay 325i, relay3% is operated over the circuit path from ground through contact tit,winding of relay interrupter contact 835, winding of magnet to battery.Magnet ttt does not operate under this condition due to the high.resistance of the winding of relay 826, and wipers 8 ll--8 l l remainconnected to terminals Edi-44 i of impulse regenerating unit ltil.

At contact 8225, relay 825i extends ground potential through contacts8l2 and to terminal Md for the purpose of busying impulse regeneratingunit lilt against possible seizure from another selector unit associatedwith another toll trunk of the polar duplex impulsing telephone system.At contact Sill, relay 82% connects the winding of relay 8313 toterminal ltl of impulse regenerating unit lllt: at contact 822, opensthe operating circuit to relay lid but relay All does not restoreimmediately dc to its slow-to-release characteristic: at contact 823,G624 to terminal M2 of impulse regenerating unit 58: at contact 82%,connects terminal "5 33 of impulse regenerating unit ltd to conductor 253 leading to impulse relay R559 of the incoming selector 5% of the tolltrunk: at contact 325 disconnects magnet 835 from terminal Hi l of implse regenerating unit 3255]; and. at contact 82, prepares a lockingcircuit to terminal its of impulse regenerating unit lelii.

Ground potential is connected .via terminal extends conductor 6. Hi! tothe junction between the upper and lower windings of relay 'l l 5, theother end of the upper winding of relay llil is connected to groundpotential, and the other end of the lower winding of relay lid isconnected to terminal id-2. The upper winding of relay iiil therefore,shortcircuited, and cattery potential from repeater 4% of the toll trunkconductor C 124 is extended to the lower winding of relay lit overterminal 742 and conductor E52, causing relay lid to operate. Relay "LGfunctions as a line impulsing relay and is fitted with micrometeradjustment means F5? for the armature which operates contacts 1 ii andH2 in order that very close adjustments of the contacts can be made. Atcontact H2, relay lid completes an obvious operating circuit to relayJ29.

At contact lie operated relay 52% connects ground potential to terminalMi -i over conductor 15 i and 15 t for the purpose of completing alooking circuit for operated relay 82d of selector unit 8%, before relaysit has had sufficient time to restore and, at contact 8l2, open theoperating circuit to relay 828. Operated relay 323i is, therefore,locked in the operated position for the time being, in order to maintaincontacts 82!, 823, S24 and 5526 closed. At contact iii, relay E20completes a circuit from battery, coil lSi, contacts E62 01 impulsespring assembly E53, switch i654, contact 'lZl, upper winding of relayM5 to ground on conductor J56, and a multiple circuit from battery, coilEdi, contacts E62, ltd, 12E, lower winding of relay H5, conductor i 53,terminal i 33, wiper contact 82 3, conductor :3 to incoming selector 5%shown in Figure 5 of the drawings of Patent No. 2,500,392, contact 534of Figure 5 of Patent No. 2,560,392, winding of impulse relay R559: toground, causing relay R560 of Patent No. 2,500,3Q2 to operate andthereby condition incoming selector 5% for being impulsed. Relay H5 ofthe present drawings, however, does not operate at this time because itswindings are connected differentially and, therefore, the presentcurrent flows through the two windings now oppose each other.

The dialing of the second digit of the directory number of calledsubstation T65! by the operator at switchboard Elli causes signal relayEH5 of repeater ldll of the toll trunk to follow the impulses of thissecond digit, in the manner explained in the specification of Patent No.2,500,392. Each time signal relay R llfi restores, it interrupts, atcontact ill), the operating circuit to control relay R3 15 of repeatertilt! and impulse relay Hit of the impulse regenerating unit H10. Also,each time signal relay R llll restores, it connects, at contact ill,ground potential through the lower windings of supervisory relay R650and impulse relay lit to ground potential on conductor its. Impulserelay lit accordingly restores. Conversely, each time signal relay BN5re-operates, it completes, at contact 376, the operating circuit tocontrol relay RM?) and impulse relay lit. Also, each time signal relayReid re-operates, it removes, at contact ill, ground potential from thelower windings of supervisory relay R 550 and impulse relay lifl.Impulse relay dill accordingly re-operates.

Each time impulse relay lid restores, a circuit is completed fromground, contact ll l, terminals M3, E62, contact E22, winding ofreceiving magnet R of the mechanical impulse regenerating device tobattery, and receiving magnet R, therefore, follows the impulses or" thesecond digit. Relay is of the slow-to release type and,

consequently, does not restore during this second series of impulses.Also at contact ill, a circuit is completed to relay 725 by way ofcontact 522, relay 125 operating with the first impulse of this secondseries and remaining operated for the balance of this impulse series.

At contact I28, relay 725 completes a circuit to marking magnet M of themechanical impulse regenerating device from ground on conductor 156',contacts I23, 123, winding of marking magnet M to battery, causingmarking magnet M to be energized for the balance of the second series ofimpulses. At contact 726, relay I25 completes an obvious circuit to thelower winding of relay 730, causing relay 530 to operate and remainoperated for the balance of the second series of impulses. At contact529, relay I25 connects a multiple ground to conductor H54 in order toprovide an additional guard period for impulse regenerating unit 700.Energized marking magnet lVi tilts lever 1563 of disc X clear of thestop pins Z for the time being, in the manner de scribed in Patent No.2,183,461.

The operation of the mechanical impulse regenerating device to receiveand transmit impulses is described in detail in Patent No. 2,188,461,and the following brief description is given in order that the operationof the device in conjunction with the control relays of the impulseregenerating unit Hi9 may be fully under stood.

Responsive to the first deenergization of receiving magnet R, theoil-normal contact 155 of the mechanical impulse regenerating device isclosed to prepare an operating circuit to relay M5, which circuit isopen at interrupter contact T58 of energized marking magnet M. Inaddition, at contact 'lSl, relay T30 completes a circuit through theupper winding of relay 740 by way of the winding of sending magnet S.Relay F 58 is thereby operated but sending magnet S does not operateowing to the high resistance of the upper winding of relay 148. Atcontact 7 l9, relay T40 short-circuits its lower winding so that relay Mis rendered slow to release. At contact ll'i, relay 7 3G causes slaverelay 135 to operate and, at contact 738, open a further point in thecircuit of a slow-to-operate alarm. Relays '525, 730, mil and 735 remainoperated until the end of the second series of impulses when relay 25restores after a short interval due to the final opening of contact Hi.lhe energizing circuit of receiving magnet R. is now open at contact H1, since the pulsing of receiving magnet R has caused the rotation ofdisc X the proper number of steps to select the stop pin Z correspondingto the value of the second series of impulses, in the manner describedin Patent No. 2,188,461.

At contact F28, relay E25 opens the energizing circuit to marking magnetM which causes interrupter :56 to close and complete the preparedcircuit to relay MS from ground, off-normal contact :55 (contact 555remaining closed until the cycling of the impulse regenerating device iscompleted subsequent to the receipt of the final series of incomingimpulses), contact 'l56, winding of relay to battery, causing relay 5 tooperate and look through contact it? to ground at oil-normal contact 233independent of contact I55. The de-energization of marking mag-- net Malso permits lever of advanced disc X to restore thereby pushing theselected stop pin Z into the path of reset pin Y. At contact I26, relayI disconnects ground potential from the lower winding of relay but relay730 does not restore before relay T25 closes contact 12'! and therebyprovides holding ground through ofi-normal contact 155 to the lowerwinding of relay 739. At contact 129, relay 125 removes a multipleguarding ground from conductor 154.

At contact F33, relay i 55 prepares a circuit to sending magnet S; atcontact "34, connects a multiple ground to conductor 15d to provide anadditional guard period for impulse regenerating unit 09: at contactT39, prepares an alarm circuit which is open at contact and, at contactM9, completes a circuit from ground, displaced stop pin Z which was leftdisplaced in the path of reset pin Y at the completion of theregeneration on the preceding call, reset pin Y, interrupter contact 158of sending magnet S, contact 149 to the junction between the lowerwinding of relay "I33 and coil 55%) to short-circuit the lower windingof relay 7353.

After a short interval, relay Z38 restores. and, at Contact 73!, opensthe circuit to the upper winding of relay "4%, the restoration of relay7 56 being delayed by its short-circuited lower winding. At contact H'l,relay MB opens the circuit of relay ":35 but relay 735 is slow inrestoring due to it: slow-to-release characteristic. The restoration ofrelay 555 completes a circuit to sending in gnet S from ground, contacts732, 73?, Z 3, winding of sending magnet S to battery, causing sendingmagnet S to energize. lhe energization of sending magnet S causesinterrupter contact 158 to open, thereby removing the short-circuitingground from the lower winding of relay 53d, and relay E36 immediatelyre-operates to open the energizing circuit of sending magnet S atcontact F32. The de-energization of sending magnet causes reset pin Y torestore the displaced stop pin Z against which it is resting, therebyfreeing disc I59 for rotation.

The restoration of relay 735 also completes the alarm circuit at contactE38, but under regular operation relay I35 will re-operate early enoughto prevent the sounding of the alarm. At contact reoperated relay E39again completes the operating circuit of relay "ME b way of the windingof sending magnet S, causing relay "f ll? to operate, but not sendingmagnet S. At contact H 9, relay "i -s9 short-circuits its lower windingto make itself slow to release at a later period. At contact iii, relayMl! again completes the circuit to and reiay T35 i e-operates to openthe alarm circuit. Should relay F35 fail to re-operate, the alarm willsound, thus. indicating irregular i'utoctioning or failure of impulsereception or regeneration.

Disc E52 rotates by spring power, in the manner described in Patent No.2,138,461, to cause reset pin Y to advance into mechanical electricalcontact with the displaced stop pin Z corresponding to the value of thesecond series of impulses. Meanwhile the dialing of the third digit bythe calling operator at switchboard 2 it causes a third series ofimpulses to be received by the impulse regenerating device. The disc Xis, therefore, adancezl to a further position where a further stop pin Zis displaced into the path of reset pin Y to register the third seriesof impulses in the manner described in Patent No. 2,188,461. It shouldbe understood at this time that the described interactions betweenrelays liid, 75D and T35 is for the purpose of providing suitablespacing between the reception and retransmission. of the impulse series.

Disc ltd drives the impulse cam 735 under the control of an adjustablespeed governor in the manner described. in Patent No. 2.188A61, andthereby transmits a series of impulses over condoctor Bi l to theimpulse relay Rli ill of the incoming selector Elli! of Patent No.2,500,392, whereupon reset pin Y of the impulse regenerating devicereaches the displaced stop pin Z corresponding to the value of thereceived second series of impulses, to lock disc lfiil against furtherrotation at thi This retransmitted series of impulses is of the correctspeed due to the governor-controlled driving of impulse cam I65, theshape of impulse cam 1765 establishes the correct ratio.

Impulse cam E55 deliver alte hate ground and battery impulses toconductor BM. The ground impulses shunt both windings of relay lit,relay H cannot operate under this condition. The battery impulses fromcam E55 cannot oper-- ate relay 7H5 because, as previously explain d,current flows through the two windings of relay l i 5 are op itedirections neutralize each other. Relay :55 of impulse regenerating unitlllll, therefore, remains dormant for the entire impulse retransmissionperiod.

Impulse relay of incoming selector 553i? now follows th impulsing of camloll. Impulse relay res .res on each ground impulse from cam 755 andre-operates on each battery impulse and. therefore, the first series ofregenerate unpuses from earn 355 cause the elevation and automaticrotation of the wipers of incoming selector to a free tollselector-repeater in. the manner described in Patent No. 2,50%,392. Theseized toll selector-repeater 8% is disclosed in Figure 6 of Patent No.2,500,392.

As reset pin Y comes into electrical contact with said second displacedstop in Z, the lower wir ing of re-operated relay is short circuitcd fom ground, said second displaced stop Z, reset pin Y, interruptercontact E58 of sending magnet S, contact 'U-i to the junction betweenthe lower winding oi relay Hill and coil i555. After a short interval.re-opcratcd relay E39 restores, and, at contact Elli, opens the circuitto the upper winding of re-operated relay Hill, the restoration ofre-operated relay lei being delayed by its therefore. again completedfrom ground, contacts 32, El, finding of sending magnet S to battery,causing sending magnet S to lB-QllfilgiZG. The re energization orsending magnet S causes interrupter contact "558 to re-open, therebyremoving the short-circuiting ground from the lower winding of relayFill, relay Fail re-operates a second time to again open the energizingcircuit of ire-energized sending magnet S at ccntact l3'2. This econdde-energization of sending magnet S causes reset Y to restore thedisplaced stop 2 against which it is now rest ing to again iree disc 559for rotation.

At contact 'i-rli, twice re-operated relay l3 again completes theoperating circuit of relay lei; by way the Winding of sending magnet S,causing relay Hill to re-operate a second time. At contact 1 i8, relayMil again short-circuits its lower winding to re-establish itsslow-to-release characteristic. At contact all, relay lei? againcompletes the circuit to relay 23 and relay lei; again re-operates.

Responsive to the seizure of toll selectorrepeater tilt, incomingselector 5% switches through in the manner described in Patent No.2,580,392, relay R536 disconnecting impulse relay REM? from conductor 8Mat contact 534 and connecting conductor Clile to conductor M4 at contact533. The impulsing circuit from impulse cam 165 of the impulseregenerating device is thereby extended to ground by way of the lowerWinding of impulse relay R6343 of the toll select0r-repeater Std andcontacts i, 648, and impulse relay Rttll operates over this extendedcircuit preparatory to pulsing toll selector-repeater tilt.

In a manner similar to that just described, impulse earn 555 of the imulse regenerating device transmits successive series of regeneratedimpulses corresponding to the third, fourth and fifth series of dialedimpulses from the calling switchboard 2 0, to first operate the tollselectorrepeater iiiill to select and seize a free toll connector B03,and then operate the seized toll connector 683 to seize and signal thecalled substation Ttfi l. The interdigital pause between the series ofregenerated impulses is determined by the serial release times of relays135, MB and 735 and. the operation and release of sending magnet S,thereby to provide longer trunk-hunting periods for the switches aheadthan would ordinarily be provided. The descriptions of the operations ofincoming selector 5%, toll selectorrepeater Elli] and toll connectorfills are contained in the specification of Patent No. 2,500,392 and,therefore, need not be repeated herein.

When all of the digits dialed at the calling switchboard 21% have beenregistered in the impulse regenerating device of impulse regeneratingunit ice and the final stop pin Z is displaced into the path of resetpin Y, disc X of the impulse regenerating device comes to rest. When allof the corresponding regenerated impulses have been transmitted byimpulse cam I55, disc l59 overtakes disc X and reset pin Y comes to restagainst the said final displaced stop pin Z preparation for the nextcall. Off-normal contact IE5 is opened, thereby unlocking relay Hi5, andrelay Hi5 restores. The opening of offnormal contact "!55 also opens theholding circult of relay ME, and relay 736 accordingly restores. Atcontact 73!, restored relay 73!! causes relay let to restore after ashort interval, and relay Hi3, at contact HT, causes relay 735 torestore in turn after a short interval.

At armature 53 5, relay M5 removes a multiple guarding ground fromconductor 754 since the impulse regenerating device has now beenreturned to normal condition in preparation for the next call. Atarmature 133, relay M5 opens a point in the operating circuit of sendingmagnet S and, at contact 739, opens a point in the mentioned alarmcircuit.

When the party at called substation T68! answers the call, batterypotential is returned over conductor Ciil i in the manner explained inPatent No. 2,500,392, and this battery potential is further extendedover conductor 8M, contact 3%, wiper 3&3, terminal M3, conductor 153 tothe lower winding of relay I I5. The lower winding of relay H5 is thuseffectively short-circuited to the battery potential from impulse cam#65 through contacts 12!, 164 and E62. As a consequence, relay ll5 isoperated over the circuit from ground on conductor 154', upper windingof relay n5, contacts l'Zi, E65, E62, coil lfil, to battery. Relay H5completes a circuit from ground, contact H6, terminals W5, lii l,conductor lfil, terminal 74!, wiper 84!, contact 82], winding of relay83B to battery, causing relay 83!] to operate and lock to the ground onconductor C423 through contact 833. At contact 832, relay switchesconductor C42 5 to conductor 8M, thereby completely switching repeater308 through to incoming selector 509. t contact 33!, relay 83E)disconnects conductor C424 from the lower winding of relay 1 E ofimpulse regenerating unit 590, causing relay III! to restore. At contact83:3, relay 83G opens the locking circult of relay 826. The restorationof relay 820 disconnects conductor 3M from the lower winding of relay H5of impulse regenerating unit 100 at contact 824; disconnects conductorC423 from conductor 'I5I at contact 82! and opens a further point in thecircuit of relay H8 at contact 323.

The restoration of relay IIEI opens the circuit of relay I at contactH2, and relay I20 restores after a short interval. Relay I and receivingmagnet R, however, are operated from ground at contact II I during theslow release period of relay I26. At contact I29, relay I25 maintainsground potential on conductor I54 for a short interval after therestoration of relay 720 to provide ample time for the completerestoration of impulse regenerating unit I99 and its associated impulseregenerating device. At contact H t, relay I2 3 removes a multipleground from conductor I54; at contact I2I, opens the holding circuitthrough the upper winding of relay H5; and, at contact I22, opens theholding circuits of relay I25 and receiving magnet R. Relays I I5, I25and receiving magnet R restore accordingly, and relay I25 removes thelast ground potential from conductor I54. Impulse regenerating unit I00is now free for use by another toll trunk of the polar duplex impulsingtelephone system.

It is unnecessary to include further details of the call betweenswitchboard 2H] and substation TGGI in the present specification, assuch details are contained in the specification of Patent No. 2,500,392.Upon the release of the connection after the conversation between thecalling and called persons has been terminated, ground is removed fromconductor CA2? thereby unlocking relay 83S. turns selector unit are tonormal condition.

Considering now the case where the calling operator at switchboard Ziaabandons a call Without completing the dialing, then relay H8 isrestored responsive to the removal of battery potential from conductor C524. At contact I12, relay :IIl opens the holding circuit of relay I20,and relay I26 restores after a short interval. The operating circuit torelay I25 and the energizing circuit to receiving magnet R arecompleted, however, during the slow release time of relay I25, fromground, contact II I, terminals IE3, IE2 and contact 122. It should beunderstood that receiving magnet R advances disc X on the releasedriveprinciple so that before disc X can be moved, relay I25 will haveoperated and energized marking magnet M by way of contacts I28 and I23,thereby to tilt lever 76!) away from the stop pin Z circle and thus freedisc X for rotation. At contact I29, relay I25 extends guarding groundto conductor 75c before relay I20 has restored.

The calling operator may abandon the call before dialing the seconddigit of the directory number of substation Tfifil, or before dialingthe third, fourth or fifth digits as circumstance dictates. In the eventthe operator abandons without dialing the second digit, then therestoration of relay 128 opens the energizing circuits of receivingmagnet R and relay I25 at The restoration of relay 83!! recontact I22,and very shortly thereafter the energizing circuit of marking magnet Mat contact 723. The de-energization of receiving magnet R causes disc Xto advance one step and select the stop pin adjacent the stop pin Zagainst which reset pin Y is resting, and the de-energization of markingmagnet M causes lever 766 to displace the selected stop pin Z into thepath of reset pin Y. As disc X moves re- 3 sponsive to thede-energization of receiving magnet R, off-normal contact I55 closes tooperate and lock relay I45, and relay I connects additional guardingground to conductor IE4 at contact I34. The restoration of relay 12!]also connects ground potential through contacts I29, I28 and 124 to thejunction between contact H9 and the lower winding of relay M0, and inthe meantime operated relay I25 has caused the successive operations ofrelays I30, ME! and 735.

The described ground potential at contact II 9, therefore, passesthrough contact H9 to energize sending magnet S before relay I 25 hadoperated and closed contact M9. The ground potential through contact H9short-circuits the upper Winding of relay 740, and shortly thereafterrelay I48 restores to open the energizing circuit of sending magnet S atcontact H9 and the holding circuit of relay 735 at contact III. Thede-energization of sending magnet S causes reset pin Y to restore thedisplaced stop pin Z against which it is resting, and disc I59 thereuponadvances reset pin Y into contact with the adjacent displaced stop pinZ. As reset pin Y comes to rest against the adjacent displaced stop pinZ, off-normal contact I opens to unlock and restore relay I45. In themeantime. restored relay 720 has opened the outgoing impulsing circuitat contact l'ZI to cause the release of conditioned incoming selector500, and the restoration of relay I25 causes the restoration of relayI30 at contact 126, the removal of guarding ground at contact I29, andthe removal of ground potential from the lower winding of relay IE0 atcontact 128. At contact 734, restored relay I45 removes the lastguarding ground from conductor I54, and impulse regenerating unit I06 isnow at normal and available for a subsequent call.

In the event the operator abandons the call after dialing the seconddigit (0, for example.) Without dialing the third digit, then relay H3restores and shortly thereafter relay I28 restores. The impulseregenerating device will have started the regeneration of the impulsesof the registered digit 0, in the manner previously explained, and resetpin Y will be automatically advanced into contact with the displacedstop pin Z corresponding to the value of the registered digit. In themeantime restored relay I20 has opened the outgoing impulsing circuit atcontact IZI to cause the release of conditioned incoming selector 500;has opened the multiple energizing circuits to relay I25 and receivingmagnet R at contact I22; and, shortly thereafter, has opened theenergizing circuit of marking magnet M at contact I23. From this pointon, the manner of restoring the impulse regencrating device to normalcondition is essentially the same as that just described for theinstance where the operator abandons a call without registering oneseries of impulses in the impulse regen rating device.

The calling operator at switchboard 2H1 can, of course, abandon a callafter having registered two, three or four digits in the impulseregencrating device. In any of these events, the restoration of theimpulse regenerating device to normal condition is similar to thatdescribed in the preceding paragraph wherein the call is abandoned afterthe second digit is dialed but not the third digit.

Regenerating network common to a group of trunks-delay in impulseretransmission As previously indicated, Figure 4 of the present drawingsshows that Figures '7, 8 and 10 are combined together to form an impulseregenerating network which is made common to a group of toll trunks of apolar duplex impulsing telephone system, and wherein the transmission ofthe regenerated impulses to the switch, or switches, ah ad is delayed toprovide additional trunk hunting time for the switch, or switches,

ahead. In the present disclosure, however, the

transmission of regenerated impulses is prevented beyond the firstswitch ahead (incoming selector 550) when incoming selector 50a isunable to find a free trunk outlet, and supervision is accordinglyrelayed back to the calling opcommon to a group of trunksNo delay inimpulse retransmission, the terminals MI-EM. of each impulseregenerating unit is made available to the banks of the selector units850 which are associated with the toll trunks of the polar dupleximpulsing telephone system.

The operation of a call originated at switchboard 2Ii for a connectionto substation T50I when relay unit I 055 is used in combination withimpulse regenerating unit I to delay the regeneration of the registeredimpulses, is the same as that described in the mentioned precedingsection of this specification up to the point where selector unit 800seizes a free impulse regenerating unit I00. From that point on, theoperation is as follows:

Ground potential is connected via contact IOI2 and terminal I0! to thejunction between the two windings of relay M0, the other end of theupper winding of relay I I El is connected to ground potential, and theother end of the lower winding of relay H5 is connected to terminal M2.The upper winding of relay H0 is, therefore, short-circuited, and thebattery potential from repeater 500 of the toll trunk over conductor C52is extended to the lower winding of relay IIEI over wiper 802, terminalI42 and conductor 752, causing relay H0 to operate. At contact I2I,relay He completes an obvious operating circuit to relay 720.

At contact H4, operated relay I20 connects ground potential to terminalI40 for completing a locking circuit for operated relay 820 of selectorunit 800 before relay 0I0 has had sufficient time to restore and openthe operating circuit of relay 820 at contact 8I2. relay I20 alsocompletes a circuit to relay I055 by way of terminal 10! and contactI038, causing rela I005 to operate. At contact I2I, relay I completes acircuit from battery, coil 15!,

At contact II4,

contacts I62, I54, I2I, upper winding of relay H5 to ground on conductorI54, and a multiple circuit from battery, coil IBI, contacts I52, I64,I2I, lower winding of relay II5, conductor I53, terminal I43, wiper 843,contact 825, conductor Bhi to incoming selector 552 of the toll trunk,contact 534 of Figure 5 of Patent No. 2,500,392, Winding of impulserelay R540 to ground, causing relay R540 to operate. Relay H5 of thepresent drawings, however, does not operate at this time because itswindings are differentially connected and, therefore, the current flowsthrough the two windings now oppose each other. At contact I046, relayI045 completes an obvious operating circuit to relay I050, but operatedrelays I045 and I050 have no function at this time.

Each time impulse relay H0 restores, responsive to the dialing of thesecond digit at calling switchboard 2I0, a circuit is completed fromground, contact II I, terminal I53, contacts IOI9, I024, terminal I02,contact I22, winding of receiving magnet R to battery, and receivingmagnet R, therefore, follows the impulses of the second digit. Also atcontact III, a circuit is completed to relay I by way of contact I22,relay I25 operating with the first impulse of this second series andremaining operated for the balance of this impulse series.

At contact I28, relay I25 completes a circuit to marking magnet M fromground on conductor I54, contacts I20, I23, winding of marking magnet Mto battery, causing marking magnet M to be energized for the balance ofthe second series of impulses. At contact I28, relay I25 also completesa circuit to rela I025 from ground on conductor I54, contacts I20, I23,terminal I06, winding of relay I025 to battery, causing relay I025 tooperate. At contact I26, relay I25 completes an obvious circuit to thelower winding of relay I50, causing relay I to operate and remainoperated for the balance of the second series of impulses. At contactI29, relay I25 connects a multiple ground to conductor I54 in order toprovide an additional guard period for impulse regenerating unit I00.Energized marking magnet M tilts lever I00 of disc X clear of the stoppins Z for the time being. At contacts I02! and I523, relay I025prepares circuits to the upper and lower windings, respectively, ofrelay I020.

Responsive to the first deenergization of receiving magnet R, theofi-normal contact I55 of the mechanical impulse regenerating device isclosed to prepare an operating circuit to relay I45, which circuit isopen at contact I55 of energized marking magnet M. Off-normal contactI55 also completes a circuit to relay I030 by way of terminal I00,contact I05I, winding of relay 030 to battery, causing relay I530 tooperate. At contact I03I, relay I030 extends its ground connection tothe upper winding of relay I020 by way of contact I02? and, at contactI052, connects ground to the lower winding of relay I020 by way ofcontact I028. Relay I020, however, does not operate at this time becauseits windings are differentially connected.

At contact I3I, relay I30 completes a circuit through the upper windingof relay 10-; by way of the winding of sending magnet S. Relay I isthereby operated but not sending magnet S. At contcat H9, relay I40short-circuits its lower winding so that relay Mil is rendered slow torelease. At contact III, relay I55 causes slave relay I35 to operateand, at contact I38, disable a slow-to-operate alarm. Relays I25, I30, Iand I35 remain operated until the end of the terrupter contact I55 toclose and complete the ":22

circuit to relay I45 from ground, off-normal contact I55, contact 756,winding of rela I45 to battery, causing relay I45 to operate and lockthrough contact I47 to ground at off-normal contact I55 independent ofcontact I56. The deenergization of marking magnet M permits lever I60 ofadvanced disc X to restore thereby pushing the selected stop pin Z intothe path of reset pin Y. At contact 128, relay I25 also opens thecircuit to relay I025, causing relay I025 to restore, At contact I25,relay I25 disconnects ground from the lower winding of relay I but relayI does not restore before relay I25 closes contact 62'! and therebyprovides holding ground through ofi-normal contacts I55 to the lowerwinding of relay 735). At contact I29, relay I25 removes a multipleguarding ground from conductor I54.

At contact I33, relay I prepares a circuit to sending magnet S; atcontact I34, connects a multiple ground to conductor I54 to provide anadditional guard period for the impulse regenerati'ng unit I58; atcontact I39, prepares an alarm circuit which is open at contact I38; andat contact I49, completes a circuit from ground, displaced stop pin Zwhich was left displaced at the completion of the regeneration on thepreceding call, reset pin Y, contact 158 of sending magnet S, contactI69 to the junction between the lower winding of relay I35 and coil I toshort circuit the lower winding of relay I30.

After a short interval, relay I30 restores and, at contact 13!, opensthe circuit to the upper winding of relay I48, the restoration of relayI49 being delayed by its short-circuited lower winding. At contact III,relay I48 opens the circuit of relay I35 but relay I35 is slow inrestoring. The restoration of relay I35 completes a circuit to sendingmagnet S from ground contacts I32, I3I, I33, winding of sending magnet FS to battery, causing sending magnet S to energize. The energization ofsending magnet S causes contact I58 to open, thereby removing theshort-circuiting ground from the lower winding of relay I39, and relayI30 re-operates to open the energizing circuit of sending magnet S atcontact I32. The de-energization of send ing magnet S causes reset pin Yto restore the displaced stop pin Z against which it is resting, therebyfreeing disc I59 for rotation.

At contact I3I, re-cperated relay I35 again completes the operatingcircuit of relay I45 by way of the winding of sending magnet S, causingrelay ltd to operate but not sending magnet S. At contact H3 re-operatedrelay I48 short-circuits its lower winding to make itself slow torelease at a later period. At contact FII, relay I40 again com'iletesthe circuit to relay E35 and relay I35 reoperates to open the alarmcircuit.

The disc rotates by spring power to cause reset spring I to advance intomechanical and electrical contact with the displaced sto pin Zcorresponding to the value of the second series of impulses. Meanwhilethe dialing of the third digit at the calling switchboard 2 I 0 causes athird series of impulses to be received by the impulse regeneratingdevice. The disc X is, therefore, advanced to a further positon where afurther stop pin Z is displaced to register the third series ofimpulses.

Disc I59 drives impulse cam I55 under the controi of the adjustablespeed governor and thereby transmits a series of impulses over conductor8 I4 to the impulse relay R545 of the incoming selector whereupon resetpin Y reaches the displaced stop pin Z corresponding to the value of thereceived second series of impulses. Alternate ground and batteryimpulses are delivered by impulse cam I in the manner described in thepreceding section of this specification. Impulse relay restores on eachground impulse from cam S65 and re-operates on each battery impulse and,therefore, the first series or" regenerated impulses from cam I55 causethe elevation and automatic rotation of the wipers 0f incoming selector550 into the bank level of trunks (such as EHO) leading to tollselector-repeaters (such as 608).

Now assuming that there is no free toll selectorrepeater (such as 8:35)then the wipers of incoming selector 5E8 are rotated to the eleventhrotary step in well-known manner. The contact sets S582, S583 and S58Iin Figure 5 of the drawings of Patent No. 2,500,392 are therebyoperated, resulting in the intermittent operation of busy relay R565 andthe consequent alternate ground and battery impulses back over conductor3 I4 by way of contact 533, in the manner described in the specificationof Patent No. 2,500,392. The ground impulses back over conductor 8Menergize the lower winding of relay H5 in the opposite direction to thecurrent flowing through the upper winding of relay H5 and relay H5,therefore, cannot operate under this condition. The battery impulsesback over conductor 8H3, however, short-circuit the lower winding ofrelay i I 5 thereby unbalancing relay H5 and permitting it to operateover the circuit from ground on conductor I54, upper winding of relay Ii 5, contacts Ht, 764, I62, coil E5! to battery. The alternateoperations and restorations of relay IE5 cause relay I935 tocorrespondingly operate and restore by way of contact H8 and terminal105. The armature of relay H5 is fitted with micrometer adjusting meansit? in order that close adjustment of contact H5 can be made.

The first operation of relay I835 causes relay I940 to operate fromground on conductor I54, terminal .Gl, contact i832, winding of relayI040 to battery, and relay I840 remains operated due to itsslow-to-restore characteristic for the balance of the pulsing of relay I835. At contact I638, relay I835 opens and closes the circuit to relayI945 but relay I045 also does not restore during the pulsing of relayI935.

At contact I636, the first operation of relay I035 causes relay ISIS tooperate by way of contacts I052, I926, Itll8 and, at contact HHS), openthe operating circuits to relay E25 and receiving magnet R. Relay IIlIIilocks to ground by way of contacts IEiII and IMI. The alternate closingsand openings of contact I535 cause relay IIlIO to correspondinglyoperate and restore by way of contacts I052 and iiil 5, thereby totransmit alternate battery and ground impulses by way of contacts IIlIIand I852, respectively, through terminal 'iOI, lower winding of relayIIII, terminal 42, wiper 8G2, contacts 523, 831, conductor C424, contact444, lower winding of supervisory relay R l5ii to battery or ground, asthe case may be. The sole function of relay iii} under thes con- 1'7ditions is to maintain relay 120 operated to hold the connection for thetime being.

In the meantime the rotation of disc 159 has caused reset pin Y toadvance into mechanical and electrical contact with the displaced stoppin Z corresponding to the value of the second series of impulses, and aground shunt is connected to the junction between the lower winding ofrelay I30 and coil E50 by way of oil-normal contact 155, displaced stoppin Z corresponding to the value of the second series of impulses, resetpin Y, contact 158 of sending magnet S and contact I43. Re-operatedrelay 130, however, cannot restore at this time because the operation ofrelay I040 responsive to the described first operation of relay I035caused re-operated relay I30 to be maintained from ground, contact I04I,terminal 108, upper winding of relay 130 to battery. As a consequence,re-operated relays I40 and I35 cannot be restored and, therefore, theoperating circuit to sending magnet S cannot be re-completed at contactsI32 and I31. In this manner, disc #53 remains locked, and theregeneration of the registered third series of impulses cannot beaccomplished. The alternate battery and ground impulses through thelower winding of relay H back over conductor C424 cause the frontsupervisory lamp L266 at the calling switchboard 2m to be flashedapproximately 120 times per minute in a manner similar to that explainedin Patent No. 2,500,392, to indicate that a busy condition in theoutgoing toll train has been encountered. The calling operator thereuponwithdraws the front plug P2 I2 from the jack J220 to effect the releaseof the apparatus involved.

Now assuming that the wipers of incoming selector 500 do find a freetrunk (such as 6E3) terminating in a free toll selector-repeater (suchas 600) then incoming selector 500 seizes toll selector-repeater 600 andswitches through in the manner described in Patent No. 2,500,392, relayR530 disconnecting impulse relay R540 from conductor 8| 4 at contact 534and connecting conductor G6 I 4 to conductor -8I4 at contact 533. Theimpulsing circuit from impulse cam I65 is thereby extended to ground byway of the lower winding of impulse relay R630 of the tollselectorrepeater 600 and contacts 654, 648, and impulse relay R630operates over this extended circuit preparatory to pulsing the tollselector-repeater 600.

Since, in this instance, the wipers of incoming selector 500 are notrotated to the eleventh step, busy relay R565 of incoming selector 500is nonresponsive and, therefore, alternate battery and ground impulsesare not returned back over conductor 8I4-only steady ground potentialthrough the lower winding of impulse relay R630 of tollselector-repeater 600 over conductor C6I4, wiper 574 of incomingselector 500, contact 533 to conductor 8I4. As a consequence, relay N ofimpulse regenerating unit 100, and relays I035 and I040 of relay unitI000 do not operate and, consequently, relay I30 cannot be retained inthe operated position through its upper winding.

Impulse regenerating unit I00, therefore, re' mains conditioned forregenerating received third, fourth and fifth series of impulses andtransmitting the regenerated series of impulses over conductor 8I4 tocause the successive operations of toll selector-repeater 600 and tollconnector 603 to select and signal called substation T60I, in amannersimilar to that explainedin the preceding'section of this specification.'When called substation T60I answers the call, the sub sequentoperation, however, varies somewhat in detail as follows:

The returning of battery potential over con ductor 6I4 causes relay "M5to close contact H6 thereby to operate relay I035 by way of terminalI05. At contact I038, relay I030 opens the circuit of relay I045,causing relay I045 to restore after a short interval and open thecircuit to relay I050 at contact I046. Relay I050 in turn restores aftera brief period and closes contact I05I. A circuit for operating relay830 of selector unit 600 is thereby completed from ground, contactsI036, I05I, terminal 104, conductor 15h terminal MI, wiper GM ofselector 800, contacts 62L winding of relay 830 to battery.-

Relay 630 locks to ground on conductor C423 through contact 833. Atcontact 032, relay 830 switches conductor C424 to conductor 8I4, therebycompletely switching repeater 400 through to incoming selector 500. Atcontact 83I, relay 330 disconnects conductor C424 from impulse re-'generating unit and, at contact 834, opens the locking circuit of relay820. Relay 820 disconnects conductor 8I4 from impulse regenerat ing unit100 at contact 024, and opens a further point in the circuit of relay H0at contact 323. The operated relays of impulse regenerating unit I00 andrelay group I000 are thereby restored, thus freeing the impulseregenerating unit I00 for use by another toll trunk.

In a manner similar to that just described for delaying the regenerationof the dialed third, fourth and fifth series of impulses when incomingselector 500 fails to find a free toll selectorrepeater (such as 600),impulse regenerating unit 100 and relay group I000 co-operate to preventthe regeneration of the dialed fourth and fifth series of impulses whenthe seized toll selector repeater 600 fails to find a free tollconnector (such as 603).

In this latter instance, the wipers of toll selector-repeater 600 arerotated to the eleventh step in well-known manner. The contact sets S66Iand S692 in Figure 6 of the drawings of Patent No. 2,500,392, arethereby operated, resulting in the intermittent operation of toll answerrelay R660. Alternate battery and ground impulses are, consequently,relayed back over conductor C6I4, through contact 533 to conductor 8I4and thence through the lower winding of relay H5. The resultingalternate battery and ground impulses through the lower winding of relayH0 back over conductor C424 cause the front supervisory lamp L266 at thecalling switchboard 2I0 to be flashed approximately times per minute toindicate that a busy condi tion has been encountered in the outgoingtoll train.

It should be understood at this time that the two foregoing examples ofdelay in impulse regeneration are typical only and that the presentinvention is not specifically limited thereto. It should also beunderstood that the present invention is not restricted to onlypreventing impulse regeneration after the transmission of the firstregenerated series of impulses has been accomplished, but is designed tore-establish the regeneration of subsequent series of impulses after aproper interval of time has elapsed following the transmission of thefirst regenerated series of impulses.

The re-establishment of impulse regeneration is accomplished by causingthe alternate battery andground impulses over conductor 8-I4'to thelower winding of relay II 5 to'cease. Relay II5 then ceases toalternately operate and restore, and comes to rest in the restoredposition. Contact IIG, therefore, remains open and relay I035 restoresfor the last time. At contact I031, relay I035 opens the circuit torelay I040 which restores in turn after a short interval. .At opencontact I041, relay I040 ceases to maintain relay I30 operated throughits upper winding, and relay 130 restores after a short interval due tothe short-circuiting of its lower winding from the ground at off-normalcontact I55 which was established in the manner previously described. Atopen contact I036, relay I035 ceases to pulse relay IOI0.

At contact 'I3I, restored relay I30 opens the circuit to the upperwinding of relay I40, causing relay I40 to restore after a shortinterval and, at contact I I 7., open the circuit to relay I35. RelayI35 restores in turn after a short interval, and the circuit to sendingmagnet S is again reestablished from ground, contacts I32, I31 and. I33,.causing the re-energization of sending magnet S. The re-energization ofsending magnet S causes interrupter contact I58 to open, therebyremoving the short-circuiting ground from the lower winding of relayI30, and relay I30 reoperates a second time to again open the energizingcircuit of re-energized sending. magnet S at contact I32. This secondde-energization of sending magnet S causes reset pin Y to restore thedisplaced stop pin Z against which it is resting. The regeneration ofthe next registered series of impulses is, therefore, started andcompleted in the manner previously explained. At contact I04I, restoredrelay I040 opens the locking circuit of relay IOI5, causing relay IOI5to restore and re-establish the circuit from contact II I of relay H atcontact IOI9. At contact IOI6, restored relay IOI opens a further pointin the pulsing circuit to relay "H0. and ground supervision is returnedback over conductor C424 by way of the lower winding of relay I I0 andconductor I52.

It is further contemplated that impulse regenerating unit I00 and relaygroup I000 be used in-co-operation with a finder method of trunkhunting, topreventimpulse regeneration until the trunk huntingof astarted finder has found afree trunk, and thereafter establish theimpulse regeneration in a manner similar to that just described in theimmediately preceding paragraphs.

As in the case of the calls described in the preceding section of thisspecification, the occupied impulse regenerating device is restored tonormal condition whenever the operator at calling switchboard 2I0abandons a call described in this section without completing the dialingof the called-substations directory number. If no trunk busy conditionis encountered on the outgoing toll train, then the restoration of theoccupied impulse regenerating device is accomplished in essentially thesame manner as that explained in the'preceding section. If, however, atrunl: busy condition was encountered in the outgoing toll train andimpulse regeneration has accordingly been stopped by the locking of discI59, then the method of restoring the occupied impulseregeneratingdevice to normal condition is accomplished in a somewhatdifferent manner as follows:

Assuming first that the operator abandons just after registering thethird digit in the impulse regenerating device, and that the impulseregenerating device is locked against regenerating the registeredthirddigit in'the manner previously explained. In this instance-justbefore abandonment, relays H5, I035 and I010 are operating and restoringalternately, and relays H0, I20, I030, IOI5, I040, I045, I050, I30, I40,I35, and I45 are in the energized position. Since relay I30 is heldenergized through its upper wind ing, the normal energizing circuit ofsending magnet 8 is retained open at contact I02. The abandonment causesrelay M0 to restore for the last time and open the holding circuit ofrelay at contact II2, causing relay I20 to restore after a shortinterval. The operating circuit to relay I25, however, cannot becompleted at contact III since it is maintained open at contact IOI0and, therefore, relay I25 cannot re-operate.

The restoration of relay I20 opens the outgoing impulsing circuit atcontact I2I to cause the release of incoming selector 500 and therestoration of relay H5. t contact II4, relay I20 opens the holdingcircuits of relays I000 and I045, causing these two relays to restoreafter a short interval. At contact I I 6, relay I I5 opens the pulsatingcircuit of relay I035, and relay I035 re stores forthe last time. Atcontact I036, relay I035 opens the pulsating circuit of relay I0 I 0,and relay IOI0 re-establishes ground potential to the junction betweenthe two windings of relay H0 at contact IOI2 but relay H0 cannotre-operate at this time. At contact I045, relay I045 opens the holdingcircuit of relay I050, causing relay I050 to restore after a briefinterval. At contact I04I, relay I040 unlocks relay IOI5, causing relayIOI5 to restore and reestablish contact II I.

The restoration of relay I040 also opens the holding circuit through theupper winding relay I30, and relay I30 restores shortly thereafterbecause ground potential by way of the displaced stop pin Z againstwhich reset pin Y is resting, reset pin Y, contacts I50, I49 to thejunction between the lower'winding of relay I30 and coil I50 eifectivelyshort-circuits said lower winding. Relays I40 and I35 restore in turn,and the energizing circuit to sending magnet S is completed by Way ofcontacts I32, I3! and I33.

The energization of sending magnet S opens contact I58, thereby removingthe short-circuiting ground from the lower winding of relay I30, andrelay I30 reoperates from ground potential by way of off-normal contactI55 and contact 121, thereby to open the energizing circuit of sendingmagnet S at contact I32. This de-energization of sending magnet S causesreset pin Y to restore the displaced stop pin Z against which it isresting thereby freeing disc I59 for rotation. Relay I30 also causes there-operation of relay I40 at contact 'ISI, and relay I00 in turn causesthe re-operation of relay I35 at contact 111.

Reset-pin Y is accordingly advanced to rest against the displaced stoppin Z which corresponds to the value of the registered third digit.Sincea fourth digit is not registered, off-normal contact opens as resetpin Y comes'to rest against the displaced stop pin Z which correspondsto the value of the registered third digit, thereby opening the holdingcircuits of relays I45, I030 and I30 and causing these three relays torestore. At contact I3 I relay 730 opens the holding circuit of relayI40, and relay I40 opens the holding circuit of relay I35. Impulseregenerating unit I00- and its associated impulse regenerating deviceare now in normal condition.

The operator at switchboard 2I0 can, of course, abandon calls afterhaving registered three or four digits-in the impulse regeneratingdevice,

with the impulse regenerating device locked against regenerating threeor four of the re istered digits, as the case may be. It is considered,however, unnecessary to include explanatory details of suchabandonments, in view of the descriptions of typical abandoned calls inthe preceding section and in this section of the specification.

Considering now the case of an attempted call wherein the number ofdialed impulses exceed the stop pin Z capacity of the impulsesregenerating device of impulse regenerating unit I00, then flashing lampsupervision is returned to the calling operator to abandon the call.This flashing lamp supervision and the restoration of the occupiedimpulse regenerating device, are accomplished in the following describedmanner.

' As lever I of disc X reaches the stop pin Z which is two pin positionsshort of the stop pin Z against which reset pin Y is now resting,ofinormal contact 155 opens. The lever I60 of disc X is then preventedfrom rotating past the next stop pin Z which is just ahead of the saidstop pin Z against which reset pin Y is resting, and when the impulsingof the dialed digit now being registered ceases, the de-energization ofmarking magnet M causes lever I60 of disc X to displace the stop pin Zwith which lever IE0 is now aligned. Reset pin Y is, therefore, nowlocated between two adjacent displaced stop pins Z, which establishes anunstandard condition.

The opening of oif-normal contact I55 unlocks relays I45 and I035, relayI45 restoring quickly and relay I035 after a short interval. Beforerelay i530 restores, however, the circuit through the upper winding ofdifferentially connected relay H320 is opened at oiT-normal contact I55,and the circuit through the lower winding of relay I020 by way ofcontact I032 causes relay 025 to operate. Relay I020 then locks toground potential on conductor I54 by way of terminal I01 and contactI022.

At contact I020, relay I020 disables contact III to prevent any furtherimpulsing into the impulse regenerating device; at contact I023, extendsthe circuit of relay I25 and receiving mag-net R to the winding of relayI055; and, at contact I02I, connects interrupted ground potential torelay IIiIIi. Relay I055 accordingly operates and relay I25 ismaintained operated, but receiving mag-' net R cannot energize throughthe winding of relay I055. At contact I056, relay I055 causes relay I050to operate. The operating circuits to relay I025 and marking magnet Mare again completed from ground on conductor I54 by way of contacts I28and I23, but relay I025 and marking magnet M have no functions toperform at this time.

Relay IOI0 follows the pulsing of the inter-'- rupted ground potentialthrough contact I02I, thereby to transmit alternate battery and groundimpulses by way of contacts I0 and IOI2, respectively, through terminalIOI, lower winding of relay I50, terminal I42, wiper 842, contacts 023,835, conductor C424, lower winding of supervisory relay R450 to batteryor ground, as the case may be. The sole function of relay H0 under theseconditions is to maintain relay I20 to hold the connection for the timebeing.

The alternate battery and ground impulses through the lower winding ofrelay H0 over conductor C424 causes the front supervisory lamp L255 atthe calling switchboard 2 I 0 to be flashed approximately 120 times perminute in a mann'er similar to that explained in Patent No.

22- 2,500,392, to indicate that an abnormal (or tinstandard) conditionhas been encountered on this call.

Since the impulse regenerating device of impulse regenerating unit I00is now in an unstandard condition with certain stop pins Z displacedinto the path of reset pin Y, it is necessary to effect its restorationto normal condition responsive to the calling operator at switchboard2I0 abandoning the call. As relay IIO restores for the last timeresponsive to the abandonment, the holding circuit to relay is opened atcontact H2, and shortly thereafter relay 120 restores.

The restoration of relay I20 opens the outgoing impulsin circuit atcontact I2I; at contact I22, opens the circuit of relays I055, I25 andreceiving magnet R; and, atcontact I23, opens the circuit to relay I025and marking magnet M. Relay I955 restores quickly, opening the circuitof relay I060 at contact I055, at contact I057, connecting groundpotential to the junction between contact ?I 9 and the lower winding ofrelay I40 by way of contact I062 and terminal II3 before relay I050 hashad sufficient time to restore. Relay I25 restores shortly after relayI055 restores, as does relay I000.

At contact I20, relay I25 unlocks relay I020, causing relay I020 torestore after a short interval and open the pulsating circuit of relayIOI0 at contact I02I and also re-establish contact II I of relay II 0 atcontact I024. Relay IOI 0 re-establishes ground potential to thejunction between the windings of relay II 0, but relay H0 cannotre-operate at this time. At contact I26, relay I25 opens the holdingcircuit of relay I30, causing relay I30 to restore after a shortinterval.

The mentioned ground potential from relay I055 energizes sendingmagnet Sby way of contact H9 (relay I40 still being in the operated positionbecause of relay I30 not havin fully restored) and also short-circuitsthe upper winding of relay I40, thereby to cause relay I40 to restoreand open the energizing circuit of sending magnet S at contact H9. Thede-energization of sending magnet S causes reset pin Y to restore thedisplaced stop pin Z against which it is resting, and disc I59 thereuponadvances reset pin Y into contact with the next displaced stop pin Z(which stop .pin Z was displaced by the first registered digit and whichregistered digit is assumed to have consisted of two or more impulses).Responsive to the advancing of disc I59, off-normal contact I55 closeswith the second step and causes relay I45 to re-operate by way ofcontact 750 and look by way of contact I4I.v At contact I34, relay I45replaces guarding ground on conductor I54.

Relay I35 having restored completely is now re-operated from ground byway of ofif-normal contact I55 and contact I21. Relays I40 and I35re-operate in turn, and the energizing circuit of sending magnet S isopen at contact I32. As reset pin Y comes to rest against displaced stoppin Z corresponding to the first registered digit, the lower winding ofrelay I30 is short-circuited from ground by way of displaced stop pin Zcorresponding to the first registered digit, reset pin Y and contacts758 and I49, and relay I30 again restores after a short interval. Atcontact I3I, relay I30 opens the holding circuit of relay I40, causingI40 to restore in turn and open the holding circuit of relay at contactIII. As relay T35 restores, sending magnet S is energized from ground byway of contacts 132,!3I-and I33.

The last mentioned energization of sending magnet S causes contact 158to remove the shortcircuiting ground from the lower winding of relay73!], and relay 139 re-operates from ground potential by way ofoff-normal contact 155 and contact I27. Relays T40 and 135 re-operate inturn, and the energizingcircuit of sending magnet S is open at contact132. Disc T59, therefore, advances reset pin Y to rest against thedisplaced stop pin Z corresponding to the second registered digit. Fromthis point on, the restoration of the impulse regenerating device iscompleted in essentially the same manner" as that explained in thepreceding section of this specification for the call to substation T60In the preceding last-described attempted call, it was assumed that thefirst registered digit consisted of two or more impulses. Assuming nowrat the first registered digit in that attempted call consisted of onlyone impulse, then oiT-normal contact 155 does not close when disc 159advances reset pin Y one step to cause reset pin Y to rest against thedisplaced stop pin Z corresponding to the first registered digit. Thereason for the non-closure of off-normal contact 755 at this time isthat two steps of reset pin .Y are required to cause elf-normal contact555 to close.

As a result of the fallure'of off-normal contact 155 to close when resetpin Y comes to rest against the displaced stop pin Z corresponding it isresting, andv disc 159 thereupon advances reset pin Y into contact withthedisplaced. stop pin Z corresponding to the first registered: digit.Since the advancement of reset-pin Y is only one" step, off-normalcontact 155 cannot close;- and relays Hi and 730,. therefore, cannotre-operate.

The restoration of relay 740 also opens the holding circuit of relay 135at contact 711, and relay 535 restores after av short interval. relay735 re-stores, however, a circuit is completed from ground, contacts132, 136, 118,148, 124,

lower winding of relay 140, winding" of sending magnet S to battery,causing relay 140' to re-' operate but not sending magnet S. At contactH9, relay 74!] extends the ground potential directly to the winding ofsending magnet S, causing sending magnet S to energize. of contact 736by the complete restoration of relay 135 causes the de-energization ofsending magnet S and the restoration of re-operated re-' lay 1'43.

The de-energization of sending magnet S causes. reset pin to restorethedisplaced stop pin Z corresponding to the. first registered digit,thereby freeing disc 158 for rotation. As reset pin Y accordinglyadvances towards the displaced stop pin Z corresponding to the secondregistered digit, off-normal contact I55 closes and completes theoperating circuits to relays 145 and 130. From this point on,.the-complete restoration of the impulse regenerating device is.accomplished in' the mannerpreviously. explained.

The opening '24 Regenerating network individual to a trunkno delay inimpulse Tea-transmission As previously indicated, Figure 5 of thepresent drawings shows that Figures 7 and 9 are cornbined together toform an impulse regenerating network which is made individual to onetoll trunk of a polar duplex impulsing telephone sys tem when thetransmission of the regenerated impulses is not to be delayed.

Assuming now that such an impulse regenerating network is required forall the toll trunks of a polar duplex impulsing telephone system, thenone switching-through relay equipment 900, as shown in Figure 9 of thepresent drawings, and one impulse regenerating unit 100, as shown inFigure '7 of the present drawings, are provided for each of the tolltrunks 390 of the polar duplex impulsing telephone system.

The outgoing conductors C42 C422, C423 and C424 of each toll trunkrepeater 4GB of the polar duplex impulsing telephone system areconnected to the respective incoming selector 5!!!) of the toll trunkand to the respective switching-through relay group 959 of theassociated regenerating network, and the incoming selector 500 of eachtoll trunk and the respective switching-through relay group 5&6 of theassociated regenerating network are connected together, as shown at theleft-hand end of Figure 9 of the present draw mgs. through relay group959 are connected respectively to the terminals '54 !'M4 of theassociated impulse regenerating unit 789 by means of the dotted-linejumpers shown at the right-hand end of Figures 9 and 8 of the presentdrawings, the selector unit are and its wipers 84!844 being eliminatedfrom consideration. In this manner, each toll trunk of the polar dupleximpulsing telephone system is fitted with its individualswitching-through relay group 98!! and associated impulse regeneratingunit T00.

Assuming further that the impulse regenerating network described in thepreceding paragraph is applied to a call from switchboard 2| E] forsubstation Tiiill, then battery potential is extended over conductorC424 through contact 9! I (Figure 9), terminals 952, M2, lower windingof relay Hi! to ground at terminal it'll, causing relay Hi! to operate.At contact H2, relay 7!!) completes an obvious operating circuit torelay 128.

At contact H4, operated relay connects ground potential to conductor754. At contact 12!, relay 128 completes a circuit from battery, coil16!, contacts E62, 164, 12!, upper winding of relay H5 to ground onconductor I54, and a multiple circuit from battery, coil 16!, contactsI62, T54, 72!, lower winding of relay H5, conductor I53, terminals M3,943, contact 9|3, conductor 9l4 to incoming selector 580 of Figure 5 ofthe drawings of Patent No. 2,500,392, contact 534,

therefore unnecessary to repeat these details.

The terminals Q H-HM of eachswitching Thedetailsof the functioning ofimpulse regenerating unit 500 are fully described in the above-mentionedsection of this specification and do not need repeating in this section.It is only necessary to read in conductor 9! 4 in place of conductortit, and to trace the circuit to incoming selector through terminal 943in place of terminal and contact M3 in place of contact 824.

Responsive to the party at called substation TOI answering the call,battery potential is returned over conductor 0 I 4, contact 9I3,terminals 043, I43, conductor I53 to the lower winding of relay H5,causing relay H5 to operate in the manner described in theabove-mentioned section of this specification. Relay H5 completes acircuit from ground, contact I I0, terminals I05, 704, conductor i5I,terminals MI, 9M, contact 9 I0, winding of relay 9 I 0 to battery,causing relay 0I0 to operate and lock to ground on conductor C423through contact 9M5. At contact 5H2, relay 0i 0 switches conductor C420to conductor 9I4, thereby completely switching repeater 400 through toincoming selector 500. At contact ill I, relay 0%!) disconnectsconductor C424 from the lower winding of relay H0, causing relay "H0 torestore. At contact 013, relay 9I0 dis- "connects conductor 0I4 from thelower winding of relay H5 and, at contact SII, disconnects conductor0425 from conductor I54.

The restoration of relay IIO opens the circuit of relay I20 at contactH2, and relay I20 restores after a short interval. Relay I25 andreceiving magnet R are operated from ground at contact Hi durin the slowrelease period of relay I20. At contact iii, relay I20 opens the holdingcircuit through the upper winding of relay 1| 5, and, at contact M2,opens the holding circuits of relay E25 and receivin magnet R. RelaysH5, 325 and receiving magnet R restore accordingly, and relay I25removes the last ground potential from conductor I54 at contact I29.

Regenerating network individual to a trun7c-- Delay in impulseretransmission As previously indicated, Figure 6 of the present drawingsshows that Figures '7, 9 and 10 are combined together to form an impulseregenerating network which is made individual to one toll trunk of apolar duplex impulsing telephone system, and wherein the transmission ofregenerated impulses to the switch, or switches, ahead is delayed toprovide additional trunk hunting time for the switch, or switches,ahead. In the present disclosure, however, the transmitting ofregenerated impulses is prevented beyond the first switch ahead.(incoming selector 500) when incoming selector 500 failsto find a freetrunk outlet, and supervision is returned to the calling operator atswitchboard M0 to. abandon the attempted connection.

To combine Figures '7, 9 and 10 to form such an impulse regeneratingnetwork, the jumpers I60, I00 and H0 shown in Figure '7 aredisconnected, the dotted line jumpers III are connected up instead, andthe terminals 94I-004 of Figure 9 are connected respectively to theterminals "MI-J44 of Figure '7.

Assuming now that suchan impulse regenerating network is required forall the toll'trunks of a polar duplex impulsing telephone system, thenone switching-through relay equipment 900-, as shown in Figure 9, oneimpulse regenerating unit I00, as shown in Figure 7, and one relay groupI000, as shown in Figure 10 are provided 26 for each of the toll trunk390 of the polar duplex impulsing telephone system.

The outgoing conductors CHI-C424 of each toll trunk repeater 400 of thepolar duplex impulsing telephone system are connected to the respectiveincoming selector 500 and to the respective switching-through relaygroup 900 of the associated regenerating network, and the incomingselector 500 of each toll trunk and therespective switching-throughrelay group 900 of the associated regenerating network are connectedtogether, as shown at the left-hand end of Figure 9 of the presentdrawings. The selector unit 800 and its wipers 04I-844 are eliminatedfrom consideration. In this manner, each toll trunk of the polar dupleximpulsing telephone system is fitted with its individualswitchingthrough relay group 900 and associated impulse regeneratingnetwork I00 and relay group I000.

Assuming further that the impulse regenerating network described in thepreceding paragraph is applied to a call from switchboard 2I0 forsubstation TO0I, then battery potential is extended over'conductor C424through contact 9 (Figure 9), terminals 942, I42, lower winding of relayI I 0, terminal IOI, contact IOI2 to ground, causing relay H0 tooperate. At contact H2, relay H0 completes an obvious operatin circuitto relay I20.

At contact H4, operated relay I20 connects ground potential to conductorI54, and also completes a circuit to relay I045 by way of terminal I0?and contact I038, causing relay I045 to operate. At contact IZI, relayI20 completes a circuit from battery, coil IEI, contacts I62, I64, lZI,upper winding of relay H5 to ground on conductor I54, and a multiplecircuit from battery, coil I6I, contacts I62, I64, I2I, lower winding ofrelay H5, conductor I53, terminals I43, 943, contact 9I3, conductor M4,to incoming selector 500 of Figure 5, contact 534, winding of impulserelay R540 to ground, causing relay R540 to operate. Relay II5 of Figure7, however, does not operate at this time because its windings aredifferentially connected. At contact I046, relay The details of thefunctioning of impulse regenerating unit I00 in combination with relaygroup I 000 are fully described in the above-mentioned section of thisspecification and do not need repeatin in thissection. It is onlynecessaryto read in conductor 9| 4 in place of conductor 8M, and totracethe circuit to incoming selector 500 through terminal 943 in placeof terminal 843 and contact 9I3 in place of contact 824.

Responsive to the party at called substation BOI answering the call,battery potential is returned over conductor 9I4, contact 9I3, terminals943, I43, conductor I53 to the lower winding of relay H5, causing relayH5 to operate in the manner described in the above-mentioned section ofthis specification. Relay H5 operates relay I035 by way of terminal I05.At contact I033, relay I030 opens the circuit 'of relay I045, causingrelay I045 to restore after a short interval and open the circuit torelay I 050 at contact I G6. Relay B59111 turn restores'after a briefinterval and closes contact IBI. VA circuit for operating relay 9H0 isthereby completed from ground, contacts I036, I 05I, terminal rec,conductor l5l, terminals MI, 9M, contact 5H5, winding of relay 9I0 tobattery, causing relay all to operate and lock to ground on conductorC423 through contact 9I5. At contact 9!2, relay 0I0 switches conductorC424 to conductor 9M, thereby completely switching repeater 400 throughto incoming selector 550. At contact 9H, relay 9| 0 disconnectsconductor C 325 from the lower winding of relay I I0, causing relay IIllto restore. At contact 9I3, relay 9H3 disconnects conductor 0M from thelower winding of relay H5 and, at contact 9I'I, disconnects conductorC423 from conductor I54.

The restoration of relay H0 opens the circuit of relay I20 at contactH2, and relay I20 restores after a short interval. Relay I25 andreceiving magnet R. are operated from ground at contact III by way ofterminal I03, contacts IllI9, I024 and terminal I02 durin the slowrelease period of relay I20. At contact I2I, relay I20 opens the holdingcircuit through the upper winding of relay H5; and at contact I22, opensthe holding circuits of'relay I25 and receiving magnet R. Relays II5,I25 and receiving magnet R. restore accordingly. At contact H6, relayII5 opens the holding circuit of relay I035, causing relay I035 torestore. At contact me, relay I25 removesthe last ground potential fromconductor I54.

Having described the invention, what is considered new and is desired tohave protected by Letters Patent is pointed out in the following claims.

What is claimed is:

1. In a telephone system, a'calling station, a repeater terminating in afirst trunk having talk, hold and control conductors, a second trunkhaving talk, hold and control conductors terminating in an automaticswitch, said switch being adapted to respond to impulses of certaincharacter and speed. an impulse regenerating unit having means forgenerating impulses of said certain character and speed, the talk andhold conductors of said first trunk being connected respectively to thetalk and hold conductors of said second trunk, means for connecting thecontrol conductor of said first trunk to said regenerating unit, a trunkline, means controlled from said calling station for seizing saidrepeater, means responsive to said seizure of said repeater for seizingsaid switch over the hold conductors of said first and second trunks,means responsive to said seizure of said repeater for seizing saidregenerating unit over the control conductor of said first trunk, meansresponsive to said seizure of said regenerating unit for connectingsaid: seized regenerating unit to the control conductor of said secondtrunk, means thereafter controlled from said calling station fortransmitting impulses over the control conductor ofsaid first trunk tocause said seized regenerating unit to generate corresponding impulsesof said certain. characterand speed and to transmit said generatedimpulses of said certain character and speed over the control conductorof saidsecond trunk, means in said seized switch responsive ,tosaid tr nm Q 0f 28. said generated impulses of saidcertain character and. speedfor operating. said seized switch to select said trunk. line,. andmeans. for completing a connection between said calling, station andsaid selected trunk line, over, the talk conductors of said first, and.vsecond. trunks.

2. The telephone system claimed inclaim 1 together with means efiectiveafter said, regenerating unit has completed its functions for switchingthe. control conductor of said first trunk from said seized regeneratingunit to the control conductor of said second trunk, and means forcompleting a. connection over the control conductor ofsaid first andsecondtrunks from said calling station. to said selected trunk line.

3. The telephone system claimed in, claim 1. together with meanseffective after said seized regenerating unit has completed itsfunctions for switching the control conductor of said first trunk fromsaid seized regenerating unit. to the control conductor of said secondtrunk, means for completing a connection between said calling stationand said, selectedtrunk line over the control conductors of said firstand second trunks, and means responsive to said switching of the controlconductor of said first trunk for causing the restoration of saidoperated regenerating unit.

4. In a telephone system as claimed in claim 1 wherein there are aplurality of impulse regenerating units accessible to, said repeater,and means including the control conductor of said first trunk' forselecting and seizing. an idle one of'said plurality of regeneratingunits.

5. In a telephone system as claimed in claim 1 wherein there are aplurality of impulse regenerating units accessible to said repeater,together with means including the control conductor of said first trunkfor selecting and seizing an idle one of said regenerating units, andmeans efiective after said seized regenerating unit has completed itsfunctions for causing the release of said operated regenerating unit andfor connecting the control conductor of said first trunk to the controlconductor of said second trunk.

6. The telephone system claimed in claim 1 together with meansresponsive to a supervisory control on said selected trunk line forreturning a supervisory signal over the control conductor of said secondtrunk, and means responsive to said supervisory signal over the controlconductor of said second trunk for disconnecting the control conductorof said second trunk from said seized regenerating unit and forswitching the control conductors of said first and second trunktogether.

'7. The telephone system claimed in claim 6 and means .for returning a.supervisory signal over the control conductors of said second and firsttrunks to said calling station.

8. In a telephone system, a calling station, an automatic switch.adapted. for responding to impulses of certain character .and speed,animpulse regenerating unit having a control conductor and means forregenerating impulses of said certain character and speed, a repeaterhaving talk, hold andecontrol conductors, the talk and hold conductorsof. said repeater terminating in said switch, means for connecting thecontrol conductor of said repeater to said regenerating unit, meanscontrolled'by said calling station for seizing said repeater, meansresponsive to said seizure of said repeater for seizing said switch overthe hold conductor of said seized repeater, means responsive to saidseizure of said repeater for seizing said regenerating unit over thecontrol conductor of said seized repeater, means responsive to saidseizure of said regenerating unit for connecting the control conductorof said seized regenerating unit to said seized switch, thereby tocondition said seized switch for operation by impulses receivable fromsaid seized regenerating unit over the control conductor of said seizedregenerating unit, means thereafter controllable by said calling stationfor transmitting impulses over the control conductor of said seizedrepeater to cause said seized regenerating unit to generatecorresponding impulses of said certain character and speed, said callingstation abandoning the call without causing impulses to be transmittedover the control conductor of said seized repeater, means responsive tosaid abandonment for disabling the hold conductor of said seizedrepeater to prepare said conditioned switch for restoration, meansresponsive to said abandonment for disabling said control conductor ofsaid seized repeater, and

means responsive to said disablement of said conductor of said seizedrepeater for disconnecting the control conductor of said seizedregenerating unit from said conditioned switch to cause the restorationof said conditioned switch.

9. The telephone system claimed in claim 8 together with means foroperating said seized regenerating unit to condition its generatingmeans for generating an impulse of said character and speed, means foroperating said conditioned generating means to generate an impulse ofsaid certain character and speed and to discharge said generated impulseinto said disconnected control conductor of said operated regeneratingunit, thereby to restore said operated generating means to normalcondition, and means for restoring said operated regenerating unit tonormal condition.

10. In a telephone system, a calling station, a first automatic switch,other automatic switches each accessible to said first switch, all saidswitches adapted to respond to impulses of certain character and speed,means for busying all said other switches against seizure by said firstswitch, an impulse regenerating unit having a control conductorterminating in said first switch, said regenerating unit also havingmeans for generating impulses of said certain character and speed, arepeater having a control conductor terminating in said regeneratingunit, means for extending said calling station to said repeater, meansthereafter controlled by said calling station for transmitting a firstand a second series of impulses over the control conductor of saidrepeater, means for registering said two transmitted series of impulsesin said regenerating unit, means responsive to the registration of saidfirst series of impulses for causing said regenerating unit to generateand transmit a corresponding series of impulses of said certaincharacter and speed over the control conductor of said regeneratingunit, means responsive to said transmission of said last generatedseries of impulses for causing said first switch to progressively testsaid busy other switches, means responsive to said first switch testingthe last busy other switch for causing said first switch to connect withan all-switch-busy position, means responsive to said first switchconnecting with said all-switch-busy position for causing said operatedfirst switch to return a supervisory signal over the control conductorof said re generating unit, and means responsive to said returnedsupervisory signal for preventing said regenerating unit from generatinga series of impulses of said certain character and speed correspondingto said registered second series of impulses.

11. The telephone system claimed in claim 10 together with meansresponsive to said returned supervisory signal for extending asupervisory signal over the control conductor of said repeater to saidcalling station.

12. The telephone system claimed in claim 11 together with meansthereafter controlled by said calling station for abandoning the call,means responsive to said abandonment for opening the control conductorof said regenerating unit, and means responsive to said abandonment forcausing said regenerating unit to generate a series of impulsescorresponding to said registered second series of impulses and to discharge said last mentioned generated series of impulses into said opencontrol conductor of said regenerating unit, thereby to restore saidregenerating unit to normal.

13. In a telephone system, a calling station, a first automatic switch,a second automatic switch accessible to said first switch, a pluralityof third automatic switches each accessible to said second switch, allsaid switches adapted to respond to impulses of certain character andspeed,'means for busying all said third switches against seizure by saidsecond switch, an impulse regenerating unit having a control conductorterminating in said first switch, said regenerating unit also havingmeans forgenerating impulses of said certain character and speed, arepeater having a control conductor terminating in said regeneratingunit, means for extending said calling station to said repeater, meansthereafter controlled by said calling station for transmitting first,second and third series of impulses over the control conductor of saidrepeater, means for registering said three transmitted series ofimpulses in said regenerating unit, means responsive to the registrationof said first series of impulses for causing said regenerating unit togenerate and transmit a corresponding series of impulses of said certaincharacter and speed over the control conductorof said regenerating unit,means responsive to said transmission of said last generated series ofimpulses for operating said first switch to seize said second switch,means responsive to said transmission of said last generated series ofimpulses for causing said regenerating unit to generate and transmitanother series of impulses of said certain character and speed over thecontrol conductor of said regenerating unit, each other generated seriesof impulses corresponding to said registered second series of impulses,means responsive to said trans mission of said other generated series ofimpulses over the control conductor of said regenerating unit and oversaid operated first switch for causing said second switch toprogressively test said busy third switches, means responsive to saidsecond switch testing the last busy third switch for causing said secondswitch to connect with an all-switch-busy position, means responsive tosaid second switch connecting with said a11- switch-busy position forcausing said operated second switch to transmit a supervisory signalover said operated first switch and the control conductor of saidregenerating unit, and means responsive to said transmission of saidsuper- 31 visory signal for locking said regenerating unit againstgenerating. a series 01 impulses ofsaid certain character and speedcorresponding to said registered third series of impulses.

14. In a polar duplex impuls ng telepho Y tem includinga repeaterconnected to a. succeeding automatic switch over a trunk having line,hold and control conductors, a calling station, an impulse regeneratingunit, said control conductor being divided, into two sections and saidregenerating unit being interposed between said repeater and said switchby means of said two sections of said control conductor, means forconnecting said calling station to said repeater, means for interceptingseries of impulses controlled from said calling station over the sectionof said control conductor extending from said repeater to saidregenerating unit, means for registering said intercepted series ofimpulses in said regenerating unit, said regenerating unit having afixed capacity for registering impulses, means responsive to theregistration of the first intercepted series of impulses for causingsaid regenerating unit to generate a corresponding series of impulsesand to transmit said last generated series of impulse intov the sectionof said control conductor extending from said regenerating unit to saidswitch, means in said switch responsive to said transmission of saidlast generated series of impulses for operating said switch,means-responsive to said operation of said switch for returning asupervisory signal to said regenerating unit over the section of saidcontrol conductor connectingsaid switch and said regenerating unit,means responsive to said transmission of said supervisory signal forlocking said regenerating unit against generating and transmittingfurther series of impulses corresponding to other series of impulsesregistered in said regenerating unit, said locking of said regeneratingunit occurring before all of the succeeding intercepted seriesofimpulseshave been registered in said regenerating unit, the number ofimpulses in the last intercepted series of impulses exceeding theremaining impulse registration capacity of said regenerating unitthereby making it impossible to register all the impulses of said lastintercepted series of impulses, means responsive to said partialregistration of said last intercepted series of impulses for causing anunstandard conditioning of said regenerating unit, means responsive tosaid unstandard conditionlng of said regenerating unit for causing asupervisory signal to be, returned to said calling station over thesection of said control conductor connecting said regenerating unit andsaid repeater, thereby to identify said unstandard condition of saidregenerating unit at said calling station, said calling stationthereupon abandoning the attempted call, and means responsive to saidabandonment for causing the release of said attempted call and therestoration of said regenerating unit to normal condition.

15. In a polar duplex impulsing telephone system including a repeaterconnected to a succeeding automatic switch over a trunk having talk holdand control conductors, said switch being adapted to respond to impulsesof certain character and speed, an impulse regenerating unit havingmeans for regenerating impulses of said certain character and speed,said control conductor being divided into two sections for interposingsaid regenerating unit between said repeater and said switch, mean forintercepting impulses transmittedinto. the section of said controlconductor extending from said repeater to said regenerating unit, saidintercepted impulses having improper characteristics for correctlyoperating said switch without regeneration, means for registering saidintercepted impulses in said regenerating unit, means responsive to saidregistration, for causing said regenerating unit to eneratecorresponding impulses of said certain character and speed and totransmit such generated impulses into the section of said controlconductor extending fromv said regenerating unit and terminating in saidswitch, thereby to operate said switch according to the value of saidgenerated impulses, and means for thereafter switching the section ofthe control conductor extending from said, repeater directly to thesection of the control conductor terminating in said switch and fordisconnecting said regenerating unit from both sections of the controlconductor.

JOHN WICKS.

REFERENCES CITED UNITED STATES PATENTS Name Date Saville Apr. 18, 1939Number

